Can’t Intake more than 7 cubes

I recently completed a six cube tray bot after previously having a dr4b bot. After a bit of work I got the six cubes to collect and stack easily but when I added a third stage to the tray my intake started having trouble collecting 7 to 9 cubes. I have gone through many variations of the intake with different compressions and wheels but none have seem to get the motors to stop stalling. Any advice would be much appreciatedimage


It looks like your angle is pretty steep. I’d recommend a shallower angle. How’s it stopping to the rollers just stop or do they keep spinning just not getting enough traction on the cube?
Edit: personal recommendation try a slightly more shallow angle to decrease weight on the rollers.


The easiest solution to that would be to switch to 18 tooth sprockets. That’s what we did and it drastically improved the intake at little expense of speed.


Like @ZackJo said, are the rollers spinning, but not moving cubes up, or do they actually stop spinning?

They stop spinning completely, if they do move they do slide against the cubes and push them up minimally

OK I’ll try it. out would you suggest I move the intakes out so there is the same clearance I have now? or should I just replace them as is?

I will try lowering the tray angle, also the motors do stop spinning. Thanks


Your angle is pretty steep so making it shallower would help.
Okay, how many rubber bands are on your compression?
Any notable friction points you can think of?


I have about eight rubber bands on each intake that has seem to work the best, any friction points I have found on the tray I have covered up with plexiglass to test it doesn’t seem to help much the main problem seems to be the weight so maybe the angle is the problem?


Move them so there is around 1/3 of an inch of overlap into the tray itself.


You need some overlap into tray. It doesn’t appear you have any. Double check that your intake is parallel to tray and that your intake spins easily by hand. Take the motor off and everything should spin easily if it doesn’t that is one problem.

Thanks for the advice, applied the changes the robot works great now can stack at least 10.

1 Like

Is it better to use smaller, 18 tooth sprockets, or larger, 84 tooth sprockets. I heard on a different post that 84 sprockets were better

There’s no such thnig as 84 tooth sprockets, there biggest are 30 teeth


In general, you should use the largest size sprocket that will fit. There are many different sizes of sprocket available.

@kmmohn’s PDF on VEX chain and sprockets contains some more useful info: Chain and sprocket systems.pdf


But the 30 tooth sprockets are still really large for an intake.

I am using 24 tooth sprockets on my intake and it works pretty well. I don’t personally recommend below 18 tooth just cause it gets a little slow and compression can be an issue.

We’re using 30T intakes and it works fine

that means you either have…
A. 100 rpm rollers
B. a small cube capacity
C. an insanely low tray angle
D. Insane building Techniques that defy gravity


Yeah, how many cubes can you get? That sounds pretty weird.

I’ve seen 200rpm 30t get 7 cubes.